Amlodipine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in cardiovascular disease

Development and validation of a highly sensitive HPLC method for quantifying cardiovascular drugs in human plasma using dual detection

Cardiovascular diseases are the major cause of global mortality, and often require the concomitant use of a number of drugs to prevent and reduce these deaths. The challenge is to find effective and accurate methods for analyzing these drugs in plasma. This research introduces an innovative, sustainable HPLC-FLD method for the concurrent determination of bisoprolol (BIS), amlodipine besylate (AML), telmisartan (TEL), and atorvastatin (ATV) within human plasma. Chromatographic separation was achieved using an isocratic elution mode on a Thermo Hypersil BDS C18 column (150 × 4.6 mm, 5.0 μm), while the mobile phase comprised of ethanol and 0.03 M potassium phosphate buffer (pH 5.2) in a 40:60 ratio, with a flow rate of 0.6 mL/min. The eluate was analyzed using UV detection within the wavelength range of 210-260 nm to confirm effective separation of the four cardiovascular drugs. For enhanced specificity, a fluorescence detector was set to 227ex/298em for BIS, 294ex/365em for TEL, 274ex/378em for ATV, and 361ex/442em for amlodipine. The method was validated following the International Council for Harmonisation (ICH) guidelines. Linearity was established within the ranges of 5-100 ng/mL for BIS and AML, 0.1-5 ng/mL for TEL, and 10-200 ng/mL for ATV, ensuring accuracy and precision. The significant of the current work represented in introduction of a highly sensitive, and selective analytical method, utilizing an economical sample preparation strategy, for the simultaneous determination of four different cardiovascular drugs (bisoprolol, amlodipine, telmisartan, and atorvastatin) in spiked human plasma. The extraction of sample was carried by liquid-liquid extraction (LLE) and analyzed by LC-fluorescence detector. The chromatographic run was short (less than10 min) which is a greet economical value.

Clinically approved representative small-molecule drugs for cardiopathy therapy

The application of therapeutic agents for cardiopathy has brought about significant advancements in the treatment of cardiovascular diseases. The intervention of small-molecule drugs has led to substantial reductions in morbidity and mortality rates, along with decreased utilization of healthcare resources. However, current treatment modalities do not exhibit uniform efficacy across all patients, and the emergence of drug resistance poses a significant challenge to further therapeutic efforts. Additionally, chronic administration of these drugs can result in toxicities, adding complexity to long-term management. This review focuses on the application of clinically approved small-molecule drugs for the treatment of cardiopathy, covering major classes such as angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, β-blockers, and sodium-glucose co-transporter 2 inhibitors. The review provides an in-depth analysis of their synthetic routes, mechanisms of action, and roles in cardiopathy treatment. It also offers perspectives on future directions in the development of next-generation cardioprotective agents, aiming to optimize therapeutic strategies for cardiovascular disease management.

Efficacy and Safety of Allisartan Isoproxil/Amlodipine in Patients With Essential Hypertension Uncontrolled by Amlodipine: A Phase III, Multicenter, Double-Blind, Parallel-Group, Randomized Controlled Trial

This study aimed to assess the efficacy and safety of a combination therapy of Allisartan Isoproxil 240 mg and Amlodipine 5 mg (ALI/AML) compared to AML 5 mg monotherapy in patients with mild-to-moderate essential hypertension. In this phase III, multicenter, double-blind, parallel-group, randomized controlled trial, patients aged 18-70 years with mean sitting systolic blood pressure (msSBP) between 140 and <180 mmHg and mean sitting diastolic blood pressure (msDBP) between 90 and <110 mmHg, following a 4-week treatment with AML 5 mg, were randomized 1:1 to receive either ALI/AML or AML once daily for 12 weeks. This 12-week double-blind period was followed by an open-label extension of ALI/AML treatment through week 52. A total of 300 patients were enrolled, with 149 and 151 patients randomly assigned to ALI/AML and AML groups, respectively. Of these, 257 patients completed the study. Baseline demographics and characteristics were comparable between groups. After 12 weeks, the reduction in msSBP (the primary endpoint) was significantly greater in the ALI/AML group compared to the AML group (-15.7 vs. -10.2 mmHg, p = 0.0019). Similarly, reductions in msDBP (-5.7 vs. -2.4 mmHg, p < 0.001) and 24-h mean ambulatory SBP and DBP (-10.4 and -7.7 mmHg vs. -5.6 and -3.8 mmHg) were more pronounced in the ALI/AML group. Additionally, a higher proportion of patients achieved both a BP response and target office BP in the ALI/AML group compared to the AML group (51.4% vs. 37.4%, 42.5% vs. 30.6%, both p < 0.05). The ALI/AML combination was generally well tolerated, and the antihypertensive effect was maintained for up to 52 weeks. In patients with essential hypertension inadequately controlled by AML, the ALI/AML combination provided superior reductions in msSBP and was significantly more effective than AML monotherapy. This once-daily single-pill combination demonstrated promising efficacy and tolerability. Trial Registration: ClinicalTrials.gov identifier: NCT06465264.

Fine-tuning Fluorescence of Amlodipine Adopting on Blocking of Photoinduced Electron Transfer (PET): Application in Human Plasma

Assessing medication adherence through the determination of antihypertensive drugs in biological matrices holds significant importance. Amlodipine (AP), a potent antihypertensive medication extensively prescribed for hypertensive patients, is particularly noteworthy in this context. This article aims to introduce a rapid, simple, improved sensitivity, and reproducibility in detecting AP in its pure form, tablet formulation, and spiked human plasma than the other reported methods. The proposed method utilizes a fluorescence approach, relying on the inhibition of the intramolecular photoinduced electron transfer (PET) effect of the lone pair of the N-atom in the primary amino moiety of AP. This inhibition is achieved by acidifying the surrounding medium using 0.2 M acetic acid. By blocking PET, the target AP drug is sensitively detected, at [Formula: see text] 423 nm over a concentration range 25-500 ng mL- 1 showcasing an exceptionally low quantitation limit of 1.41 ng mL- 1. Notably, this innovative technique was successfully applied to detect AP in its solid dosage form and spiked human plasma. Remarkably, matrix interference was found to be insignificant, underscoring the robustness and applicability of the established approach. The combination of speed, sensitivity, and reproducibility makes this method particularly suitable for assessing medication adherence in patients prescribed AP for hypertension.

Effect of High-Fat Meal on the Pharmacokinetics and Safety of Valsartan/Amlodipine Fixed Dose Combination Tablets in Healthy Subjects

Background

The objective of this study was to evaluate the effect of a high-fat meal on the pharmacokinetics and safety of 80/5 mg valsartan/amlodipine tablets in healthy subjects.

Subjects and Methods

These results were derived from a bioequivalence trial where subjects were randomly assigned to take valsartan/amlodipine 80/5mg under fed conditions or after a high-fat meal contained 978.6 kilocalories (54.6% from fat). The blood samples were collected and plasma concentrations of valsartan/amlodipine were measured using high-performance liquid chromatography-mass spectrometry. The non-compartmental module of Phoenix WinNonlin Version 8.2 was used to calculate pharmacokinetic parameters. The BE module of WinNonLin was used to analyze the statistics of the maximum plasma concentration (Cmax), the area under the concentration-time curve from zero to the last quantifiable time point (AUC0-t), and the area under the concentration-time curve from zero to infinity(AUC0-∞) in plasma. 88 healthy subjects were enrolled and divided into in a fasted group and a fed group.

Results

The Cmax, AUC0-t, and AUC0-∞ of valsartan in plasma under fed conditions were 51%, 56%, and 57% lower, respectively, than those under fasted conditions, and the 90% confidence interval (90% CI) were outside the 80.00-125.00% range. All the pharmacokinetic parameters for amlodipine under fed conditions were similar to those observed under fasted conditions, and the 90% CIs were within the 80.00-125.00% range. The incidence of treatment emergent adverse events (TEAE) was similar between the fasted group and the fed group, while adverse drug reaction (ADR) was more frequent in the fasted group which may be related to the higher blood concentrations of valsartan, but all were mild.

Conclusion

The result indicated that the high-fat meal had a significant effect on the pharmacokinetics of valsartan, but no effect on amlodipine. All treatments were safe and well tolerated in healthy subjects under fed and fasted conditions.

Extemporaneous combination therapy with amlodipine/zofenopril in hypertensive patients: a real-world data analysis in Italy

OBJECTIVES

To provide clinical characteristics and to quantify the number of patients receiving the extemporaneous combination of the calcium channel blocker amlodipine and the angiotensin converting enzyme inhibitor zofenopril in a real-world setting. This evidence can provide a snapshot of the potential users of the two molecules in a single pill combination (SPC).

METHODS

Retrospective observational study using data from the IQVIA Italian Longitudinal Patient Database. Adult patients firstly prescribed with amlodipine and zofenopril between 1 July 2011 and 30 June 2020 were identified and demographic and clinical characteristics were extracted. Treatment adherence was evaluated as proportion of days covered (PDC). The potential number of patients eligible for a SPC was calculated.

RESULTS

A population of 2394 hypertensive patients, mean age of 68.6 years ±12.7, 52.6% male were treated with amlodipine and zofenopril. The majority of patients (54.5%) were low adherent (PDC <40%), 25.9% were intermediate adherent and only 19.6% were high adherent (>80%) to therapy. Around 42,500 adult hypertensive patients were estimated to be prescribed the extemporaneous combination in 2019 in Italy, being potentially eligible for treatment with amlodipine and zofenopril SPC.

CONCLUSIONS

The administration of the extemporaneous combination of zofenopril and amlodipine in hypertensive patients is a common practice in Italy. The development of a SPC can be a viable treatment option to simplify therapy and to increase adherence in hypertensive patients who are already on the two monotherapies in combination.

Utilization of erythrosine B in spectrofluorimetric quenching analysis of amlodipine and perindopril in pharmaceutical and biological matrices

A spectrofluorimetric approach that is sensitive, simple, validated, and cost-effective has been proposed for the estimation of amlodipine (AML) and perindopril (PER) in their bulk powders, pharmaceutical formulations, and spiked human plasma. The recommended approach utilized the quantitative quenching effect of the two cited drugs on the fluorescence intensity of erythrosine B, as a result of complex binary reactions among each drug with erythrosine B at pH 3.5 (Teorell and Stenhagen buffer). The quenching of erythrosine B fluorescence was recorded at 554 nm after excitation at 527 nm. The calibration curve was detected in the range 0.25-3.0 μg ml-1 , with a correlation coefficient of 0.9996 for AML, and 0.1-1.5 μg ml-1 , with a correlation coefficient of 0.9996 for PER. The established spectrofluorimetric approach was validated for the estimation of the cited drugs with high sensitivity regarding International Council on Harmonization guidelines. Therefore, the established approach could be utilized for quality control of the cited drugs in their pharmaceutical formulations.

Cinnamon modulates the pharmacodynamic & pharmacokinetic of amlodipine in hypertensive rats

The objective of this study was to investigate the effects of cinnamon on the pharmacodynamic (PD) & pharmacokinetic (PK) of amlodipine in hypertensive rats. The hypertensive control group of Wistar rats received L-NAME (40 mg/kg, daily, orally) only. The cinnamon group of rats was treated with cinnamon (200 mg/kg, daily, orally) along with L-NAME. Following 14 days treatment period, blood pressures of rats were monitored at designated intervals over 24 h utilizing a tail-cuff system for measuring blood pressure. To assess the oral PK; amlodipine was administered as a single oral dose of 1 mg/kg to rats and blood samples were collected at specified intervals over 24 h and analysed by UPLC-LC MS/MS. Synergistic decreased in rat's blood pressure was observed in presence of cinnamon + amlodipine. Simultaneous administration of cinnamon ameliorates the Cmax and AUC0-t of amlodipine, the Cmax and AUC0-t was 11.04 ± 1.01 ng/ml and 113.76 ± 5.62 ng h/ml for the cinnamon + amlodipine group as compared to 4.12 ± 0.49 ng/ml and 48.59 ± 4.28 ng h/ml for the amlodipine alone group. The study demonstrates that the use of cinnamon considerably decreases the blood pressure levels and enhances the PK parameters of amlodipine in hypertensive rats.

Efficacy and safety of bisoprolol 5 mg plus amlodipine 5 mg in patients with hypertension uncontrolled on monotherapy with 5 mg of amlodipine, a phase III multicenter, randomized, double-blind, placebo-controlled clinical trial - the AMCOR study

OBJECTIVE

To evaluate the antihypertensive effect and safety of bisoprolol 5 mg (BISO5mg) and amlodipine 5 mg (AMLO5mg) combination in comparison to AMLO5mg in hypertensive subjects uncontrolled with AMLO5mg.

METHODS

Phase III, prospective, randomized, double-blind, placebo-controlled, 8-week trial with parallel design (EudraCT Number: 2019-000751-13).

RESULTS

367 patients aged 57.58 ± 14.62 years were randomized to BISO5mg once daily on top of AMLO5mg (n = 181) or placebo on top of AMLO5mg (n = 186). Systolic/diastolic blood pressure (SBP/DBP) in the bisoprolol-treated group was reduced by 7.2 ± 12.74/3.95 ± 8.85 mmHg at 4 weeks (both p < .0001) and by 5.5 ± 12.44/3.84 ± 9.46 mmHg at 8 weeks (p < .0001/p < .0002) compared to placebo control. Bisoprolol-treated group had lower heart rate than placebo control (difference -7.23 ± 9.84/-6.25 ± 9.26 beats per minute at 4 and 8 weeks, respectively, both p < .0001). Both target SBP and DBP was achieved at 4 weeks by 62 vs. 41% (p = .0002) and at 8 weeks by 65 vs. 46% (p = .0004) of bisoprolol-treated patients and placebo group patients, respectively. SBP <140 mmHg was achieved at 4 and 8 weeks in 68 and 69% of bisoprolol-treated patients and 45 and 50% of placebo group patients, respectively. No deaths and serious adverse events were reported. Adverse events occurred in 34 bisoprolol-treated patients vs. 22 patients in the placebo group (p = .064). Bisoprolol was withdrawn due to adverse events in 7 patients, mostly (n = 4) due to asymptomatic bradycardia.

CONCLUSIONS

Addition of bisoprolol to patients uncontrolled with amlodipine monotherapy significantly improves blood pressure control. We can expect additional 7.2/3.95 mmHg SBP/DBP lowering effect by adding bisoprolol 5 mg to amlodipine 5 mg.

Fusion assays for screening of fusion inhibitors targeting SARS-CoV-2 entry and syncytia formation

Virus fusion process is evolutionarily conserved and provides a promising pan-viral target. Cell-cell fusion leads to syncytial formation and has implications in pathogenesis, virus spread and immune evasion. Drugs that target these processes can be developed into anti-virals. Here, we have developed sensitive, rapid, adaptable fusion reporter gene assays as models for plasma membrane and alternative fusion pathways as well as syncytial fusion in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and have confirmed their specificity using neutralizing antibodies and specific protease inhibitors. The fusion report gene assays are more sensitive and unbiased than morphological fusion assay. The fusion assays can differentiate between transmembrane serine protease 2 (TMPRSS2)-dependency in TMPRSS2(+) cells and trypsin-dependency in angiotensin-converting enzyme 2 (ACE2)(+)TMPRSS2(-) cells. Moreover, we have identified putative novel fusion processes that are triggered by an acidic pH with and without trypsin. Coupled with morphological fusion criteria, we have found that syncytia formation is enhanced by TMPRSS2 or trypsin. By testing against our top drug hits previously shown to inhibit SARS-CoV-2 pseudovirus infection, we have identified several fusion inhibitors including structurally related lopsided kite-shaped molecules. Our results have important implications in the development of universal blockers and synergistic therapeutics and the small molecule inhibitors can provide important tools in elucidating the fusion process.

Control Strategy for Excipient Variability in the Quality by Design Approach Using Statistical Analysis and Predictive Model: Effect of Microcrystalline Cellulose Variability on Design Space

Although various quality by design (QbD) approaches have been used to establish a design space to obtain robust drug formulation and process parameters, the effect of excipient variability on the design space and drug product quality is unclear. In this study, the effect of microcrystalline cellulose (MCC) variability on drug product quality was examined using a design space for immediate-release tablets of amlodipine besylate. MCC variability was assessed by altering the manufacturer and grade. The formulation was developed by employing the QbD approach, which was optimized using a D-optimal mixture design. Using 36 different MCCs, the effect of MCC variability on the design space was assessed. The design space was shifted by different manufacturers and grades of MCC, which resulted in associations between the physicochemical properties of MCC and critical quality attributes (CQAs). The correlation between the physicochemical properties of MCCs and CQAs was assessed through a statistical analysis. A predictive model correlating the physicochemical properties of MCCs with dissolution was established using an artificial neural network (ANN). The ANN model accurately predicted dissolution with low absolute and relative errors. The present study described a comprehensive QbD approach, statistical analysis, and ANN to comprehend and manage the effect of excipient variability on the design space.

Optimization of Personalized Amlodipine Dosing Strategies for Children Based on Pharmacokinetic Data from Chinese Male Adults and PBPK Modeling

For children, a special population who are continuously developing, a reasonable dosing strategy is the key to clinical therapy. Accurate dose predictions can help maximize efficacy and minimize pain in pediatrics. Methods: This study collected amlodipine pharmacokinetics (PK) data from 236 Chinese male adults and established a physiological pharmacokinetic (PBPK) model for adults using GastroPlus™. A PBPK model of pediatrics is constructed based on hepatic-to-body size and enzyme metabolism, used similar to the AUC_0-∞ to deduce the optimal dosage of amlodipine for children aged 1–16 years. A curve of continuous administration for 2-, 6-, 12-, 16-, and 25-year-olds and a personalized administration program for 6-year-olds were developed. Results: The results show that children could not establish uniform allometric amplification rules. The optimal doses were 0.10 mg·kg⁻¹ for ages 2–6 years and −0.0028 × Age + 0.1148 (mg/kg) for ages 7–16 years, r = 0.9941. The trend for continuous administration was consistent among different groups. In a 6-year-old child, a maintenance dose of 2.30 mg was used to increase the initial dose by 2.00 mg and the treatment dose by 1.00 mg to maintain stable plasma concentrations. Conclusions: A PBPK model based on enzyme metabolism can accurately predict the changes in the pharmacokinetic parameters of amlodipine in pediatrics. It can be used to support the optimization of clinical treatment plans in pediatrics.

Direct Visualization of Amlodipine Intervention into Living Cells by Means of Fluorescence Microscopy

Amlodipine, a unique long-lasting calcium channel antagonist and antihypertensive drug, has weak fluorescence in aqueous solutions. In the current paper, we show that direct visualization of amlodipine in live cells is possible due to the enhanced emission in cellular environment. We examined the impact of pH, polarity and viscosity of the environment as well as protein binding on the spectral properties of amlodipine in vitro, and used quantum chemical calculations for assessing the mechanism of fluorescence quenching in aqueous solutions. The confocal fluorescence microscopy shows that the drug readily penetrates the plasma membrane and accumulates in the intracellular vesicles. Visible emission and photostability of amlodipine allow confocal time-lapse imaging and the drug uptake monitoring.

BCS-based biowaivers: Extension to paediatrics

A BCS-based biowaiver allows extrapolation of drug product bioequivalence (when applicable) based on the BCS class of the drug and in vitro dissolution testing. Drug permeability and solubility considerations for adult BCS might not apply directly to paediatric subpopulations and bridging of adult and paediatric formulations should be undertaken with caution. The aims of this study were to: (i.) identify compounds which would change drug solubility classification in the paediatric population, and (ii.) to assess the risk of extending BCS-based biowaiver criteria into paediatric products of these compounds. Amoxicillin, prednisolone, and amlodipine were selected as the model compounds. Dissolution studies of IR formulations of these compounds were conducted with USP II (paddle) and mini-paddle apparatus, in media of three pHs (pH 1.2, 4.5 and 6.8). Three dissolution setups were tested: (1) 'typical' BCS-based biowaiver conditions, (2) "BE" setup derived from BE study protocols (volume: 250 mL), and (3) "paediatric" setup based on representative volume for the paediatric population (50 mL). Results revealed that extension of regulated BCS-based biowaiver criteria for paediatric application is not as simple as scaling down volumes. It was further shown that BCS-based biowaiver criteria should not be applied when there is the risk of change of the drug solubility class, from the adult to paediatric populations. A deeper knowledge of the paediatric gastrointestinal environment is still lacking and would assist in refining the biopharmaceutical tools needed to appropriately evaluate formulation performance across age groups. This would potentially reduce the number of clinical studies required and speed up formulation development.

Pharmacogenomics of amlodipine and hydrochlorothiazide therapy and the quest for improved control of hypertension: a mini review

Blood pressure (BP) is a complex trait that is regulated by multiple physiological pathways and include but is not limited to extracellular fluid volume homeostasis, cardiac contractility, and vascular tone through renal, neural, or endocrine systems. Uncontrolled hypertension (HTN) has been associated with an increased mortality risk. Therefore, understanding the genetics that underpins and influence BP regulation will have a major impact on public health. Moreover, uncontrolled HTN has been linked to inter-individual variation in the drugs’ response and this has been associated with an individual’s genetics architecture. However, the identification of candidate genes that underpin the genetic basis of HTN remains a major challenge. To date, few variants associated with inter-individual BP regulation have been identified and replicated. Research in this field has accelerated over the past 5 years as a direct result of on-going genome-wide association studies (GWAS) and the progress in the identification of rare gene variants and mutations, epigenetic markers, and the regulatory pathways involved in the pathophysiology of BP. In this review we describe and enhance our current understanding of how genetic variants account for the observed variability in BP response in patients on first-line antihypertensive drugs, amlodipine and hydrochlorothiazide.

Probing the interaction between levamlodipine and hemoglobin based on spectroscopic and molecular docking methods

In recent years, levamlodipine (LAML) has been widely used as a common drug for the treatment of hypertension. However, no reports exist that focus on the binding process of LAML with the transport proteins present in blood circulation. Here, several spectroscopy techniques, molecular docking and a molecular dynamics simulation were employed to comprehensively analyze the mechanism underlying the interaction between bovine hemoglobin (BHb) and LAML, as well as the effect of other drugs on the BHb-LAML system. The results indicated that a stable BHb-LAML complex was formed and that the binding site for LAML was located at β-37 tryptophan in the central cavity of BHb. Van der Waals force and hydrogen bonds played major roles in this binding process, and the number of binding sites (n) in the binary system was approximately equal to 1. Multiple spectroscopy experiments (FT-IR and three-dimensional fluorescence spectrometry) and a dynamics simulation revealed that LAML could induce a conformational in BHb and that the microenvironment of Trp/Tyr changed. Interestingly, the values of the binding constant between LAML and BHb significantly increased due to the effect of rofecoxib, propranolol and enalapril. Meanwhile, these drugs did not produce synergistic or negative synergistic effects on the LAML binding with BHb. These results provide new insight into the transport mechanisms for LAML in the human body.

Synthesis and Pharmacological Screening of Pyridopyrimidines as Effective Anti-Diarrheal Agents through the Suppression of Cyclic Nucleotide Accumulation

The increased levels of cyclic nucleotides (cGMP and cAMP) in enterocytes trigger intracellular mechanisms of ion and fluid secretion into the lumen, causing secretory diarrhea. Twelve novel pyridopyrimidines derived from 5‐(3,5‐bistrifluoromethylphenyl)‐1,3‐dimethyl‐5,11‐dihydro‐1H‐indeno[2,1 : 5,6]pyrido[2,3‐d]pyrimidine‐2,4,6‐trione (FPIPP) were synthesized and evaluated on intracellular cyclic nucleotide accumulation. All compounds had no effect on either cyclic nucleotide basal levels or on pre‐contracted aortic rings. The metabolic activity and viability in T84 cells, assessed by MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide) and the LDH (lactate dehydrogenase) assays, respectively, were not affected by incubation with the compounds (50 μM). Compound VI almost abolished cGMP accumulation (94 % inhibition) induced by STa toxin in T834 cells and significantly reduced (69 %) forskolin‐induced cAMP accumulation in Jurkat cells. Compound VI was active in an in vivo model for diarrhea in rabbits. These results prompted us to perform a microscopic histopathological analysis of intestinal tissues, showing that only compound VI preserves the intestine without significant pathological changes and with a decreased inflammatory pattern in comparison to FPIPP. In vitro stability test revealed that compound VI is resistant to oxidation promoted by atmospheric oxygen.

Identification and structure elucidation of a new degradation impurity in the multi-component tablets of amlodipine besylate

New unknown impurity at m/z 421.15 was observed during the accelerated stability analysis (40 °C/75% relative humidity) in the multi-component tablets of amlodipine besylate by reversed-phase ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS). UHPLC-MS and nuclear magnetic resonance (NMR) techniques were employed to identify and fully characterize the degradation compound. The degradation product was unambiguously identified as 3-ethyl 5-methyl 4-(2-chlorophenyl)-6-methyl-2-(morpholin-2-yl)-1,4-dihydropyridine-3,5-dicarboxylate and mechanism of its formation was proposed. It was confirmed that the degradation product was formed by the reaction of amlodipine with formaldehyde originating from the excipients present in the dosage form.

Comparative pharmacokinetics of a fixed-dose combination vs concomitant administration of telmisartan and S-amlodipine in healthy adult volunteers

Objective

This study compared the pharmacokinetic (PK) and safety profiles of a fixed-dose combination (FDC) formulation of telmisartan and S-amlodipine with those of concomitant administration of the two drugs.

Materials and methods

This was an open-label, randomized, crossover study in healthy male Koreans. All subjects were administered an FDC tablet containing 40 mg telmisartan and 5 mg S-amlodipine and were also coadministered the same dose of both drugs given separately. The crossover study design included a 14-day washout period between the two treatments. Blood samples were collected up to 168 h following drug administration. The plasma concentrations of telmisartan and S-amlodipine were determined by liquid chromatography tandem mass spectrometry. PK parameters and plasma concentration–time curves were compared. Safety was assessed by measuring vital signs, clinical laboratory tests, physical examinations, and patient interviews.

Results

The geometric mean ratios and 90% CIs for the maximum plasma concentration (C_max) and area under the curve from time zero to the last sampling time (AUC_t) were 0.8782 (0.8167–0.9444) and 0.9662 (0.9210–1.0136) for telmisartan and 1.0069 (0.9723–1.0427) and 1.0324 (0.9969–1.0690) for S-amlodipine, respectively. A total of 36 adverse events (AEs) were reported by 23 subjects, but no statistical differences were observed between the two treatments. The most frequently reported AE was a mild-to-moderate headache that was generally self-limiting.

Conclusion

For both telmisartan and S-amlodipine, the C_max and AUC_t 90% CIs were between ln (0.8) and ln (1.25). These results suggest that the FDC formulation is pharmacokinetically bioequivalent and has a similar safety profile to the coadministration of these drugs.

Fixed-dose combination orally disintegrating tablets to treat cardiovascular disease: formulation, in vitro characterization and physiologically based pharmacokinetic modeling to assess bioavailability

Cardiovascular disease (CVD) is the leading cause of death among men and women worldwide. In CVD, hypertension and dyslipidemia commonly coexist and are managed through coadministration of amlodipine and atorvastatin, respectively. The case for fixed-dose combination (FDC) oral dosage forms and orally disintegrating tablet (ODT) technology to enhance outcomes and compliance is strong. This work follows the development and characterization of single and FDC ODTs containing amlodipine and atorvastatin, followed by bioequivalence comparison between these single and FDC formulations, using in vitro dissolution and Caco-2 apparent permeability (Papp) and in silico physiologically based pharmacokinetic modeling approaches. ODTs containing amlodipine (5 mg) and atorvastatin (10 mg) either alone or in combination rapidly disintegrated (<30 s) while displaying a radial crushing strength in excess of 100 N and friability ≤1%. In vitro dissolution test was performed in fasted and fed-state simulated intestinal fluid (FeSSIF) and analyzed using high-performance liquid chromatography. Dissolution profiles for single and FDC ODTs were compared using US FDA recommended difference (f1) and similarity (f2) factor testing for bioequivalence. In all cases, there was no difference in active pharmaceutical ingredient dissolution between single or FDC ODTs, with the exception of amlodipine in FeSSIF. Pharmacokinetic clinical trial simulations were conducted using Simcyp (Version 14), incorporating Papp and dissolution data. Simulated clinical trials in healthy volunteers showed no difference in bioavailability based on pharmacokinetic parameters between single and combination doses with either active pharmaceutical ingredient. An increase in Cmax and AUC for atorvastatin in fed subjects was attributed to extended transit along the gut lumen and reduced atorvastatin metabolism due to lower CYP3A4 expression at more distal small intestine absorption sites. The results demonstrated bioequivalence of an FDC ODT for amlodipine and atorvastatin, while highlighting several limitations of f1 and f2 bioequivalence testing and strengths of mechanistic pharmacokinetic modeling for oral drug absorption.

Amlodipine-Induced Bilateral Upper Extremity Edema

Objective:

To report a case of bilateral upper extremity edema associated with amlodipine use in a child.

Case Summary:

A previously well and normotensive 6-year-old girl presented with a generalized vasculitis of unknown origin and severe hypertension. Large vessels predominantly affecting the neck, chest, and abdomen were found to be involved, resulting in abnormal arterial circulation and significant blood pressure differences between the upper and lower extremities. Multiple antihypertensive agents were initially required to control blood pressure. She was stabilized and discharged on amlodipine 10 mg each evening, atenolol 50 mg/day, and warfarin. Three days later she was noted to have facial and bilateral upper extremity pitting edema. Laboratory and radiologic assessments for possible etiologies were negative. Discontinuation of amlodipine resulted in resolution of edema.

Discussion:

As of June 2007, there had been no cases of bilateral upper extremity edema associated with amlodipine use reported in the English literature. Adverse effects of amlodipine, a widely used antihypertensive, have been well reported. These include flushing, headache, and peripheral edema. Lower limb edema is the most common, while periocular and perioral edema have occurred less frequently. Anasarca edema has been described only once in the English literature. According to the Naranjo probability scale, amlodipine was a probable cause of bilateral upper extremity edema in this child.

Conclusions:

Bilateral upper extremity edema has been associated with amlodipine use in a child with an abnormal arterial circulation. The edema resolved upon discontinuation of the drug.

Quantitative model for the blood pressure-lowering interaction of valsartan and amlodipine

AIMS

The objective of this study was to develop a population pharmacokinetic (PK) and pharmacodynamic (PD) model to quantitatively describe the antihypertensive effect of combined therapy with amlodipine and valsartan.

METHODS

PK modelling was used with data collected from 48 healthy volunteers receiving a single dose of combined formulation of 10 mg amlodipine and 160 mg valsartan. Systolic (SBP) and diastolic blood pressure (DBP) were recorded during combined administration. SBP and DBP data for each drug alone were gathered from the literature. PKPD models of each drug and for combined administration were built with NONMEM 7.3.

RESULTS

A two-compartment model with zero order absorption best described the PK data of both drugs. Amlodipine and valsartan monotherapy effects on SBP and DBP were best described by an I_max model with an effect compartment delay. Combined therapy was described using a proportional interaction term as follows: (D₁  + D₂ ) +ALPHA×(D₁ × D₂ ). D₁ and D₂ are the predicted drug effects of amlodipine and valsartan monotherapy respectively. ALPHA is the interaction term for combined therapy. Quantitative estimates of ALPHA were -0.171 (95% CI: -0.218, -0.143) for SBP and -0.0312 (95% CI: -0.07739, -0.00283) for DBP. These infra-additive interaction terms for both SBP and DBP were consistent with literature results for combined administration of drugs in these classes.

CONCLUSION

PKPD models for SBP and DBP successfully described the time course of the antihypertensive effects of amlodipine and valsartan. An infra-additive interaction between amlodipine and valsartan when used in combined administration was confirmed and quantified.

Bisoprolol/amlodipine combination therapy improves blood pressure control in patients with essential hypertension following monotherapy failure

OBJECTIVE

The efficacy of a bisoprolol/amlodipine fixed-dose combination (FDC) in patients with essential hypertension who had not responded to bisoprolol or amlodipine monotherapy was investigated.

RESEARCH DESIGN AND METHODS

In an 18 week, multicenter, randomized, comparative phase III study (ClinicalTrials.gov identifier: NCT01977794), patients with blood pressure uncontrolled by bisoprolol or amlodipine monotherapy (5 mg OD) began treatment with bisoprolol/amlodipine FDC 5/5 mg OD. Patients with controlled blood pressure (BP) at week 6/12 continued at current FDC strength, and patients with uncontrolled BP received FDC dose uptitration (maximum dose: 10/10 mg). The primary efficacy endpoint was change in systolic blood pressure (SBP) at week 18 versus baseline (corresponding to SBP under monotherapy), and secondary endpoints included change from baseline in SBP after week 6/12 and percentage of BP-controlled patients at week 6, 12 and 18. Safety was assessed by number/types of adverse events (AEs).

RESULTS

Two hundred patients were randomized to treatment (100 with uncontrolled BP under bisoprolol and 100 under amlodipine monotherapy). Overall, 196 patients were eligible for analysis. The patient groups displayed similar mean SBP reductions from baseline by study end (bisoprolol monotherapy failure: 25.9 ± 12.82 mmHg reduction; amlodipine monotherapy failure: 24.7 ± 11.67 mmHg reduction; p < 0.001 for both). Overall mean SBP decreased by 25.3 ± 12.25 mmHg (p < 0.001). Mean heart rate reductions were also observed (bisoprolol monotherapy failure: 6.6 ± 9.67 bpm reduction; amlodipine monotherapy failure: 11.5 ± 8.65 bpm reduction; p < 0.001 for both). Most patients (83.2%) displayed BP control with bisoprolol/amlodipine 5/5 mg at 6 weeks. Treatment was well tolerated at all dose levels; treatment-related AEs (mostly of mild/moderate intensity) were reported by 52.5% of patients, with no severe or serious treatment-related AEs reported. As the study focused on hypertension, total cardiovascular risk was not assessed.

CONCLUSIONS

Bisoprolol/amlodipine FDC therapy is associated with significant BP improvements in patients with essential hypertension following monotherapy failure.

Perindopril/amlodipine (Prestalia(®)): a review in hypertension

Perindopril, an ACE inhibitor, and amlodipine, a dihydropyridine calcium channel blocker, are established antihypertensive agents with complementary mechanisms of action. Recently, a once-daily, orally-administered, fixed-dose combination (FDC) of perindopril arginine plus amlodipine besylate (Prestalia(®); hereafter referred to as perindopril/amlodipine FDC) was approved in the USA for the treatment of hypertension. This article reviews the efficacy and tolerability of perindopril/amlodipine FDC and briefly summarizes the agent's pharmacologic properties. As demonstrated in short-term randomized controlled trials, perindopril/amlodipine FDC was significantly more effective in reducing blood pressure (BP) than monotherapy with either of the component drugs, and it appeared to be more effective than an up-titration scheme using valsartan and valsartan/amlodipine. The FDC agent was generally well tolerated, with the most common adverse events (peripheral edema, cough, headache, and dizziness) being consistent with the well-defined tolerability profiles of the individual component drugs. Furthermore, perindopril/amlodipine FDC was associated with a numerically lower incidence of peripheral edema compared with amlodipine monotherapy. Thus, perindopril/amlodipine FDC represents a useful option for the treatment of hypertension, including as initial therapy for patients likely to require multiple drugs to achieve their BP targets.

Treatment of Hypertensive Patients with a Fixed-Dose Combination of Bisoprolol and Amlodipine: Results of a Cohort study with More Than 10,000 Patients

Introduction

Many patients need more than one antihypertensive agent for effective blood pressure (BP) control. Prescription of a fixed-dose combination (FDC) of bisoprolol and amlodipine in one tablet has been shown to significantly improve patient adherence. This non-interventional study investigated the effects on adherence and BP control of switching from a free-dose combination of the two antihypertensive substances to a FDC in a larger patient population.

Methods

Patients aged ≥18 years with essential hypertension were switched at least 4 weeks prior to study initiation from a free-dose combination of bisoprolol and amlodipine to the FDC. Dosage adjustment was implemented only if medically indicated. Adherence was assessed on the basis of the ratio of pills used to pills dispensed (%) at each visit (pill count). BP and key laboratory values were determined at baseline, 3 and 6 months.

Results

10,532 patients (average age 59 years; 48% female) were recruited between 2013 and 2014; 22% of patients had type 2 diabetes and 38% had cardiovascular disease. The mean doses of the freely combined drugs prior to switching were 5.5 mg bisoprolol and 6.1 mg amlodipine once daily. The mean daily doses prescribed in the FDC were 5.8 and 6.4 mg, respectively. Pill counts at 6 months revealed a good to excellent adherence in >95% of the patients. Comparison of BP at baseline and at 6 months showed substantial changes (mean systolic BP: 147.3 vs. 130.9 mmHg; mean diastolic BP: 87.9 vs. 79.1 mmHg). Clinically relevant improvement in systolic BP was established for 82% of patients. In patients with comorbidities, switching to FDC produced a substantial improvement in BP. A total of 89 (0.7%) adverse events (AEs) were reported, including edema, headache, dizziness, bradycardia, nausea, and skin reactions. Only three AEs were classified as serious.

Conclusion

These data from a non-interventional study in a large patient population demonstrate the benefits of prescribing a FDC of bisoprolol–amlodipine in terms of an excellent adherence and an associated improvement in control of previously elevated BP, which may be relevant in real-life practice.

Funding

Merck KGaA.

Electronic supplementary material

The online version of this article (doi:10.1007/s40119-015-0045-z) contains supplementary material, which is available to authorized users.

Benefits of a fixed-dose combination of bisoprolol and amlodipine in the treatment of hypertension in daily practice: results of more than 4000 patients

OBJECTIVE

The study objective was assessing patient adherence to a fixed-dose combination (FDC) of bisoprolol and amlodipine in daily practice in patients who had been switched from the free to the fixed-dose combination prior to recruitment.

MATERIAL AND METHODS

The non-investigational study was carried out in Poland. Patients over 18 years of age with essential hypertension were recruited if they had already been switched from a free combination to the FDC at least 4 weeks prior to recruitment. Exclusion criteria included pregnancy, lactation, any contraindication to the FDC, and other antihypertensive treatment. Adherence was measured by tablet count (tablets taken divided by tablets prescribed, times 100) and defined as follows: excellent >90%, good 76-90%, moderate 51-75%, bad ≤50%. Other patient data, clinical findings and laboratory values were recorded upon availability at study start, after 3 months (voluntary) and after 6 months.

RESULTS

Data of 4288 patients (mean age: 59 years; gender: 50% each) were documented. The average daily doses of the FDC were 5.8 mg bisoprolol and 6.4 mg amlodipine. These doses differ only slightly from those of the free combination. After 3 months' treatment with the FDC, a dose increase was carried out in 113 patients for bisoprolol and in 126 for amlodipine. After 6 months of FDC treatment, 82% of the participants of the study showed excellent adherence and for a further 15% the adherence could be considered good. This strong adherence may have led to the observed reduction in systolic and diastolic blood pressure of 11% (Cohen's D efficient size 1.23). In addition, pulse pressure decreased from 58.8 mm to 52.2 mm. Also in diabetic patients (21% of the cohort), further reduction of systolic blood pressure values could be achieved (mean before 150 mm, after 133), wherein the initial differences compared to patients without diabetes had disappeared. The pulse rate also changed from 75 b/min to 68 b/min under the FDC.

CONCLUSION

These study results clearly show that the FDC leads to excellent patient adherence and therefore may result in better blood pressure control. Blood pressure control is crucial in the risk reduction of cardiovascular events. The key limitation of this study is that the study design does not allow a direct comparison of patient adherence under the free and the fixed-dose combination.

Amlodipine passage into breast milk in lactating women with pregnancy-induced hypertension and its estimation of infant risk for breastfeeding

BACKGROUND

Few clinical reports have been published on amlodipine passage into breast milk in lactating women.

OBJECTIVES

The aims of this study were to evaluate the plasma concentration of amlodipine and its passage into breast milk in lactating women with pregnancy-induced hypertension and to estimate the risk for breastfeeding infants.

METHODS

Thirty-one lactating women receiving oral amlodipine once daily for pregnancy-induced hypertension were enrolled. Pre-dose plasma and milk concentrations of amlodipine were determined at day 6 or later after starting the medication. Relative infant dose (RID) as an infant risk for breastfeeding was calculated by dividing the infant dose via milk by the maternal dose.

RESULTS

The mean maternal dose of amlodipine was 6.0 mg. The medians of the plasma and milk concentrations of amlodipine were 15.5 and 11.5 ng/mL, respectively. Interindividual variation was observed in the amlodipine dose and body weight-adjusted milk concentrations (interquartile range [IQR], 96.7-205 ng/mL per mg/kg). The median and IQR of the amlodipine concentration ratio of milk to plasma were 0.85 and 0.74 to 1.08, respectively. The medians of infant birth weight and daily amlodipine dose via milk were 2170 g and 4.2 μg/kg, respectively. The median of the RID of amlodipine was 4.2% (IQR, 3.1%-7.3%).

CONCLUSION

Lactating women with pregnancy-induced hypertension had higher plasma concentrations of amlodipine during the early postpartum period. Oral amlodipine transferred into breast milk at the same level as that of plasma. However, the RID of amlodipine in most patients was less than 10%.

Efficacy and safety of the dual L- and T-type calcium channel blocker, ACT-280778: a proof-of-concept study in patients with mild-to-moderate essential hypertension

ACT-280778 is an oral, non-dihydropyridine, dual L-/T-type calcium channel blocker. This phase 2a, double-blind, randomized, placebo- and active-controlled study investigated the efficacy and safety of 10 mg ACT-280778. Patients with mild-to-moderate essential hypertension received once-daily placebo (n=53), ACT-280778 10 mg (n=52) or amlodipine 10 mg (n=54) for 4 weeks. The primary end point was the change from baseline to week 4 in placebo-adjusted mean trough sitting diastolic blood pressure (SiDBP) with ACT-280778. Tolerability was assessed by recording treatment-emergent adverse events (TEAEs). Baseline clinical characteristics were similar across groups. No significant difference was observed at week 4 in mean trough SiDBP between placebo (-9.9 (95% confidence limit (CL) -12.7, -7.0) mm Hg) and ACT-280778 (-9.5 (-12.4, -6.5) mm Hg; P=0.86); amlodipine reduced mean trough SiDBP by -16.8 (-19.0, -14.5) mm Hg, confirming assay validity. Change in mean PR interval at week 4 (pre-dose) differed between placebo (-1.0 (95% CL -4.4, 2.3) ms) and ACT-280778 (6.5 (3.5, 9.6) ms); amlodipine did not increase PR interval (1.1 (-1.6, 3.9) ms).Treatment-emergent adverse events (TEAE) frequency was 32.1% (placebo), 32.7% (ACT-280778) and 33.3% (amlodipine). The most common TEAEs were headache, peripheral edema, hypertension and second-degree atrioventricular block. ACT-280778 (10 mg) did not lower blood pressure in mild-to-moderate hypertension.

Development and Validation of a LC-MS/MS Method for the Simultaneous Estimation of Amlodipine and Valsartan in Human Plasma: Application to a Bioequivalence Study

A reliable, simple, and robust liquid chromatography-tandem mass spectro-metric (LC-MS/MS) method has been developed and validated that employs solid-phase extraction for the simultaneous estimation of amlodipine and valsartan in human K₃EDTA plasma using amlodipine-d4 and valsartan-d9 as internal standards. Chromatographic separation of amlodipine and valsartan was achieved on the Luna C18 (2)100A (150 × 4.6 mm, 5 μm) column using acetonitrile: 5 mM ammonium formate solution (80:20, v/v) as the mobile phase at a flow rate of 0.8 mL/min in isocratic mode. Quantification was achieved using an electrospray ion interface operating in positive mode, under multiple reaction monitoring (MRM) conditions. The assay was found to be linear over the range of 0.302–20.725 ng/mL for amlodipine and 6.062–18060.792 ng/mL for valsartan. The method has shown good reproducibility, as intra- and interday precisions were within 10% and accuracies were within 8% of nominal values for both analytes. The method was successfully applied for the bioequivalence study of amlodipine and valsartan after oral administration of a fixed dose of the combination. Additionally, as required by the current regulatory bodies, incurred sample reanalysis was performed and found to be acceptable.

Pharmacokinetics, tolerability, and safety of the single oral administration of AGSAV301 vs Exforge: a randomized crossover study of healthy male volunteers

BACKGROUND AND OBJECTIVE

Valsartan, an angiotensin receptor blocker, is often used with calcium channel blockers (CCBs) such as amlodipine to control hypertension. Recently, the fixed-dose combination (FDC) of amlodipine 10 mg/valsartan 160 mg (Exforge) was approved. Amlodipine is a racemic mixture of CCB; S-amlodipine has higher activity than R-form. Therefore, AGSAV301, the FDC of S-amlodipine 5 mg/valsartan 160 mg was recently developed. The objective of this study was to compare the pharmacokinetic (PK) characteristics of S-amlodipine and valsartan when administered as one tablet each of Exforge and AGSAV301 to healthy male subjects.

METHODS

This was a single-dose, randomized, open-label, two-way, two-period crossover study. Each subject received a single dose of AGSAV301 and Exforge, separated by a 3-week washout period. Plasma samples for the PK analysis of valsartan and S-amlodipine were collected at predose (0) and 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 16, 24, 36, 48, 72, 96, 120, and 168 h after administration. Tolerability was also evaluated.

RESULTS

A total of 29 subjects were enrolled; 24 completed this study. The S-amlodipine maximum plasma concentration (C max) geometric mean ratio (GMR) between AGSAV301 and Exforge was 0.951 (90 % CI 0.983-1.014), and area under the concentration-time curve from time 0 to last measured time point (AUClast) was 0.917 (90 % CI 0.861-0.976). The GMR of valsartan C max was 0.994 (90 % CI 0.918-1.076), and the AUClast was 0.927 (90 % CI 0.821-1.047). All adverse events (AEs) were resolved without sequelae; no serious AEs were reported. Two drugs showed similar tendencies to lower blood pressure in healthy subjects.

CONCLUSIONS

The PK profiles of AGSAV301 and Exforge were bioequivalent. Both drugs were also well tolerated, with comparable AE profiles and similar blood pressure-lowering tendencies in healthy volunteers, suggesting equivalent therapeutic indications.

Simultaneous determination of amlodipine, valsartan and hydrochlorothiazide by LC-ESI-MS/MS and its application to pharmacokinetics in rats

Polypill is a fixed-dose combination that contains three or more active ingredients used as a single daily pill to achieve a large effect in preventing cardiovascular disease with minimal adverse effects. A novel and accurate liquid chromatography tandem mass spectrometry method using electrospray ionization mode has been developed and validated for the simultaneous determination of amlodipine (AMD), valsartan (VAL) using losartan (LOS) as an internal standard (IS), and hydrochlorothiazide (HCT) using furosemide (FSD) as an IS. The separation was carried on Aquasil C₁₈ (50 mm×2.1 mm, 5 µm) reversed phase column using acetonitrile and water containing 0.1% formic acid (50:50, v/v) as the mobile phase. The method was validated in terms of linearity, accuracy and precision over the concentration range of 1–1000 ng/mL. The intra and inter-day precision and accuracy, stability and extraction recoveries of all the analytes were in the acceptable range. This method can be successfully applied to the pharmacokinetic study of AMD, VAL and HCT when given as a polypill.

Development of a pharmacokinetic interaction model for co-administration of simvastatin and amlodipine

A model for drug interaction between amlodipine and simvastatin was developed using concentration data obtained from a multiple-dose study consisting of single- and co-administration of amlodipine and simvastatin conducted in healthy Koreans. Amlodipine concentrations were assumed to influence the clearance of simvastatin and simvastatin acid, which as well as the oral bioavailability was allowed to vary depending on genetic polymorphisms of metabolic enzymes. Covariate effects on drug concentrations were also considered. The developed model yielded a 46% increase in simvastatin bioavailability and a 13% decrease in simvastatin clearance when amlodipine 10 mg was co-administered. When CYP3A4/5 polymorphisms were assessed by a mixture model, extensive metabolizers yielded a decrease in simvastatin bioavailability of 81% and a decrease in simvastatin clearance by 4.6 times as compared to poor metabolizers. Sixty percent of the usual dose was the optimal simvastatin dose that can minimize the interaction with amlodipine 10 mg. Age and weight had significant effects on amlodipine concentrations. In conclusion, this study has quantitatively described the pharmacokinetic interaction between simvastatin and amlodipine using a modeling approach. Given that the two drugs are often prescribed together, the developed model is expected to contribute to more efficient and safer drug treatment when they are co-administered.

Simultaneous determination of losartan, losartan acid and amlodipine in human plasma by LC-MS/MS and its application to a human pharmacokinetic study

INTRODUCTION

A simple, rapid and sensitive liquid chromatography-tandem mass spectrometric assay method has been developed and fully validated for simultaneous quantification of losartan and its active metabolite, losartan carboxylic acid, and amlodipine in human plasma. Irbesartan was used as an internal standard.

MATERIALS AND METHODS

The analytes were extracted from human plasma samples by solid-phase extraction technique using Oasis HLB cartridges, (Waters Corporation, Mumbai, India). The reconstituted samples were chromatographed on a C18 column by using an 85:15, v/v mixture of methanol and 0.1% v/v formic acid as the mobile phase at a flow rate of 1.0 mL/min. A detailed validation of the method was performed as per the FDA guidelines.

RESULTS

The calibration curves obtained were linear (r ≥ 0.99) over the concentration range of 0.5-1000 ng/mL for losartan and for its active metabolite losartan acid and 0.05-10.1 ng/mL for amlodipine. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits.

CONCLUSIONS

A run time of 2.5 min for each sample made it possible to analyze more than 300 plasma samples per day. The proposed method was found to be applicable to clinical studies.

Irbesartan/amlodipine: a review of its use in adult patients with essential hypertension not adequately controlled with monotherapy

Combination therapy is often required in patients with hypertension, and fixed-dose single-pill combinations have been shown to provide an easier regimen for patients, improving adherence. Irbesartan/amlodipine (Aprovasc®) is an angiotensin-receptor blocker/calcium-channel blocker fixed-dose single-pill combination, whose constituent drugs exert additive effects when coadministered. In two randomized, open-label, multicentre, phase III trials, fixed-dose combination therapy with irbesartan/amlodipine was more effective than continuation of irbesartan or amlodipine monotherapy in patients with hypertension not adequately controlled with initial irbesartan or amlodipine monotherapy; there was a significantly greater decrease from baseline in mean seated home systolic blood pressure (primary endpoint) with the fixed-dose combination. The fixed-dose combination was also associated with a greater decrease in mean seated home diastolic blood pressure and mean seated office systolic and diastolic blood pressure than monotherapy. The fixed-dose combination of irbesartan/amlodipine was well tolerated in these patients; most treatment-emergent adverse events were of mild or moderate severity. The most frequent adverse event was peripheral oedema, generally associated with amlodipine treatment.

Population Pharmacokinetics of Amlodipine in Hypertensive Children and Adolescents

A population pharmacokinetic study was conducted in 74 hypertensive children (mean age 10.4 +/- 4.4 years [mean +/- SD]) receiving amlodipine (mean dose 0.17 +/- 0.13 mg/kg/d) chronically. Multiple blood samples were obtained from each subject to characterize amlodipine pharmacokinetics. Plasma amlodipine concentrations were determined by liquid chromatography/mass spectrophotometry with multiple-reaction monitoring detection. Population pharmacokinetic analysis was performed using NONMEM. Amlodipine concentrations were similar in subjects dosed either once or twice daily. Amlodipine pharmacokinetics were well described by a 1-compartment model with first-order absorption and elimination. For a subject at the population median weight (45 kg), predicted apparent clearances (CL/F) were 23.7 L/h for males and 17.6 L/h for females, and the apparent volume of distribution (V/F) was 25.1 L/kg. Dosing frequency did not appear to affect amlodipine concentrations in children. Weight-adjusted CL/F and V/F of amlodipine in younger children were significantly greater than in older children, suggesting a need for higher doses when treating young children with amlodipine.